Biomedical subjects

Y Wada

Publications and source records attributed to Y Wada.

At least 379 records · Page 21Linked to original sources

PubMed1998

Effect of several hydrophilic polymers on the permeation of morphine and salicylic acid through excised hairless rat skin.

Several hydrophilic polymers changed the cumulative amount of morphine (MOR) permeated through excised hairless rat skin from 1% MOR hydrochloride solution containing ethanol and l-menthol at concentrations of 40% and 5%, respectively, as permeation enhancers. Anionic polymers (carboxyvinylpolymer and methylvinylether-maleic anhydride copolymer) in the test solutions decreased the skin permeation of MOR, whereas cationic polymers (polyethyleneimine and chitosan) increased it, compared with that without polymers. Little change, however, was observed by the addition of nonionic polymers (hydroxypropylcellulose and polyethyleneoxide). On the other hand, the cationic and anionic polymers in the test solutions decreased and increased, respectively, the skin permeation of salicylic acid (SA) from the same enhancing system containing sodium salicylate. These opposite results were probably caused by the change in escaping tendency of the drugs from the vehicles, which was due to the drug-polymer interaction. (The escaping tendency has a great effect on the drug partition from the polymer solution to the skin barrier). The effect of hydrophilic polymers on the partition was then evaluated by Donnan membrane theory. The partition of MOR was increased and decreased by the presence of polymers having identical and opposite charge to MOR. The low partition of the drugs to skin may also be caused by low diffusion of the drugs in the polymer solutions. The drug release from the hydrophilic polymer solutions was then measured, and the release rate was found to have decreased in the presence of polymers having opposite charge to MOR and SA. It is suggested that these drug-polymer interactions changed the drug partition to skin thus changing the skin permeation of the drug.

Analgesics, Opioid↗

PubMed1998

Variation of monoamines and their metabolite contents in the cerebrospinal fluid of conscious rats.

To study the circadian rhythm of the monoamine and metabolite contents, cerebrospinal fluid was taken from the cisterna magna through a polyethylene catheter tube every 4 hr in the conscious rat. Norepinephrine and 3-methoxy-4-hydroxy-phenylglycol were found to describe a rhythm with the maximal content occurring during the dark phase and the minimal content occurring during the light phase. Dopamine levels increased significantly during the light phase compared with the dark phase. These results, given that cerebrospinal fluid can be taken chronically from conscious rats, indicate that our present method may be suitable for estimating changes in brain monoamine and metabolite contents.

3,4-Dihydroxyphenylacetic Acid↗

PubMed1998

Chronic inhibition of nitric oxide in central nervous system does not cause hypertension.

Acute inhibition of nitric oxide (NO) synthase in the brain causes elevation of blood pressure and sympathetic excitation under anesthetized conditions. To investigate chronic effects of NO synthase inhibition in the central nervous system on blood pressure regulation in conscious unrestrained animals, we administered NG-monomethyl-L-arginine (L-NMMA), a potent NO synthase inhibitor, at low (22.5 mumol/kg) and high (67.5 mumol/kg) doses for 1 wk into the cisterna magna with an osmotic pump and measured mean arterial pressure (MAP) and heart rate (HR) by a telemetry method. The same dose of NG-monomethyl-D-arginine (D-NMMA), an inactive isomer of L-NMMA, was administered to control rats. Chronic intracisternal administration of low-dose L-NMMA significantly decreased the brain nitrite/nitrate and NO metabolite contents as compared with D-NMMA (p < 0.05). However, MAP and its variability, HR and its variability, and plasma norepinephrine levels did not differ between the two groups of rats at either low- or high-dose treatment. Thus, chronic NO synthase inhibition in the central nervous system did not affect systemic hemodynamics or plasma norepinephrine concentrations despite the inhibition of brain NO. Our results suggest that endogenous NO in the central nervous system, at least as a whole, may not affect the systemic hemodynamics of chronic unanesthetized rats.

Animals↗

PubMed1998

Hereditary orotic aciduria heterozygotes accompanied with neurological symptoms.

We report a family with hereditary orotic aciduria heterozygotes. A 3-year-old boy who had been diagnosed as having cerebral palsy and mental retardation presented himself with an increase in excretion of urinary orotic acid. Enzymatic studies revealed that the boy and his healthy mother were hereditary orotic aciduria heterozygote carriers. We can not prove that this pyrimidine disorder caused his neurological symptoms, but his pyrimidine nucleoside supply may have been insufficient in his neonatal period.

Cerebral Palsy↗

PubMed1998

[A boy highly suspected of Shwachman syndrome].

We encountered a boy highly suspected of Shwachman syndrome. The affected child presented a mild disturbance of the extrapancreatic secretory function followed by a marked decrease in the number of peripheral blood neutrophils and contracted respiratory infections repeatedly. The neutrophilic function of the affected child showed the disturbance of motility both in vivo and in vitro. So the impairment of the neutrophil itself was considered accountable for it. After admission, he contracted a variety of viral infections and then showed an increase in the number of peripheral blood neutrophils. Furthermore, the disturbance of the extrapancreatic secretory function is also improved slowly. Shwachman syndrome is a rare disease in Japan. From the clinical course of this case, it may be reasonable to infer that there are various variant types in Japan.

Cell Movement↗

PubMed1998

[Disorders associated with aging of blood vessels and scavenger receptors].

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Aged↗

PubMed1998

Possible prediction of adverse reactions to fluorouracil by the measurement of urinary dihydrothymine and thymine.

Dihydropyrimidine dehydrogenase (DPD) deficiency with a defect of the pyrimidine catabolic pathway has recently become the focus of considerable attention, due to the severe 5-fluorouracil (5-FU) toxicities occurring in DPD deficiency patients. Studies also suggest that 5-FU toxicities could occur in another pyrimidine metabolic disorder, dihydropyrimidinuria (DHPuria). This study shows that urinary dihydrothymine (DHT) and thymine (THY) are useful indexes for detection of DPD deficiency and DHPuria. We measured urinary DHT and THY in 276 Japanese adults to establish reference ranges. When males and females were compared, both DHT and THY levels were found to be significantly higher in females. The reference ranges (mean +/- SD with logarithmic values) for males were found to be 1.56-5.70 micromol/g of creatinine for DHT and 0.40-1.47 micromol/g of creatinine for THY. The reference ranges for females were found to be 1.89-8.33 micromol/g of creatinine for DHT and 0.58-2.30 micromol/g of creatinine for THY. In addition to this study we analyzed a DPD deficiency case and a DHPuria case. In the DPD deficiency case, the THY concentrations of all urine samples were out of the reference range. However, uracil levels in most of the samples were within the normal range. The DHPuria case excreted large amounts of DHT and dihydrouracil, both out of the normal range.

Adolescent↗

PubMed1998

[Inhibition of return to object-bound location in identification and localization tasks].

Inhibition of return (IOR) refers to a bias against returning visual attention to a location that has been previously attended to. Two experiments examined the functional representations of IOR. In the localization task (Experiment 1B), there was IOR based on both object-bound and retinal coordinate representations, but no IOR for the identification task (Experiment 1A) or temporal feature (stimulus orientation or location) matching tasks (Experiments 2A and 2B). The selective occurrence of IOR in the localization task suggests that IOR may be an adaptative bias in the visual control of action. The neural basis of IOR is discussed in terms of two distinct functional pathways (perception and action) of visual system.

Attention↗

PubMed1998

[Slowly progressive aphemia--a case report].

A 69-year-old women was admitted to Tokyo Medical and Dental University Hospital because of slowly progressive difficulty in speech production over 8-years. On admission, her spontaneous speech was non-fluent, limited to one-syllable utterance, and severely efforty. But her visual and auditory comprehension was preserved. There was no significant general intellectual deterioration. Severe buccofacial apraxia, but no swallowing was observed. So we considered her difficulty in speech as aphemia. Three-dimensionally reconstructed surface MR image clearly showed severe atrophy in the posterior part of the left inferior frontal gyrus and the lower part of the left pre-central gyrus. The FDG-PET demonstrated a focal hypometabolism in the same region. The lesion in this area was suggested to be a cause of speech production difficulty in this case.

Aged↗

PubMed1998